Melt Production and Antimicrobial Efficiency of Low-Density Polyethylene (LDPE)-Silver Nanocomposite Film

Colloidal silver nanoparticles with a size of 5.5 ± 1.1 nm were prepared by chemical reduction using polyethylene glycol (PEG). Silver nanoparticles were incorporated into low-density polyethylene (LDPE) by melt blending and subsequent hot pressing at 140 °C to produce nanocomposite film with an average thickness of 0.7 mm. PEG was added at 5% weight of polymer as a compatibilizer agent in order to prevent agglomeration and provide uniform distribution of nanoparticles in polymer matrix. Antimicrobial activity of silver nanocomposites against Escherichia coli ATCC 13706, Staphylococcus aureus ATCC12600, and Candida albicans ATCC10231 was evaluated by semi-qualitative agar diffusion test and quantitative dynamic shake flask test. Mechanical properties of nanocomposites were not significantly different from silver-free LDPE-containing PEG films (p > 0.05), and silver nanoparticles did not form chemical bonding with the polymer. LDPE-silver nanocomposite samples by more than 6.69 ppm silver nanoparticles showed considerable antimicrobial clear zone. LDPE-silver nanocomposite affected growth kinetic parameters of the examined bacteria and is more efficient on S. aureus than E. coli. Polyethylene-silver nanocomposites containing 22.64 ppm silver nanoparticles could reduce 57.8% growth rate and 23.3% maximum bacterial concentration and increase 35.8% lag time of S. aureus. This study shows the potential use of LDPE-silver nanocomposite as antimicrobial active film. Antimicrobial efficiency of silver nanocomposite depends on silver nanoparticles concentration; however, high level of silver nanoparticles may lead to weakening of mechanical properties.     

Survivable millimeter-wave mesh networks

Millimeter-wave mesh networks have the potential to provide cost-effective high-bandwidth solutions to many current bandwidth-constrained networks including cellular backhaul. However, the availability of such networks is severely limited due to their susceptibility to weather, such as precipitation and humidity. In this paper, we present a rigorous approach to survivable millimeter-wave mesh networks based on experimentation, modeling, and simulation. Individual link performance is characterised using frame error-rate measurements from millimeter-wave transmissions on test links over a period of one year. A geometric model based on radar-reflectivity data is used to characterise rain storms and determine their impact on spatially correlated links of a mesh network. To mitigate the impact of link impairments on network services, we present two cross-layered routing protocols to route around the failures: P-WARP (predictive weather-assisted routing protocol) and XL-OSPF (cross-layered open shortest-path first). We conduct a performance analysis of the proposed mesh network under the presence of actual weather events as recorded by the US National Weather Service. Results show that the proposed approach yields the highest dependability when compared against existing routing methods.     

A correlation-based ant miner for classification rule discovery

In recent years, a few sequential covering algorithms for classification rule discovery based on the ant colony optimization meta-heuristic (ACO) have been proposed. This paper proposes a new ACO-based classification algorithm called AntMiner-C. Its main feature is a heuristic function based on the correlation among the attributes. Other highlights include the manner in which class labels are assigned to the rules prior to their discovery, a strategy for dynamically stopping the addition of terms in a rule’s antecedent part, and a strategy for pruning redundant rules from the rule set. We study the performance of our proposed approach for twelve commonly used data sets and compare it with the original AntMiner algorithm, decision tree builder C4.5, Ripper, logistic regression technique, and a SVM. Experimental results show that the accuracy rate obtained by AntMiner-C is better than that of the compared algorithms. However, the average number of rules and average terms per rule are higher.     

啤酒酵母和乳酸菌发酵棕榈粕渣饲料制备工艺的响应面优化

通过单因素实验和响应面法对啤酒酵母和乳酸菌发酵棕榈粕渣饲料制备工艺进行研究。结果表明:基料制备最佳发酵条件为发酵时间5 d、棕榈仁渣目数70目、菌料比1∶103、发酵温度30℃、含水量36%,该条件下基料中总菌落数为7.20×10~(10)个/g;发酵产物最佳发酵条件为发酵温度30℃、棕榈果渣与空果串配比1∶2、棕榈果渣及空果粉碎长度4 cm、配料比1∶10(基料与棕榈果渣和空果串质量比)、含水量35%、发酵时间36 d,该条件下发酵产物营养成分OD值为0.966。对发酵饲料主要成分进行分析,其粗蛋白、粗脂肪、粗纤维、粗灰分、钙、磷、含水量分别为7.20%、7.61%、26.20%、5.20%、0.38%、0.26%、16.20%,总菌落数为9.0×10~7个/g。该发酵方法工艺简单,具有良好的工业化生产前景。     

Effects of dynamic vulcanization on tensile,morphological, and swelling properties of poly(vinyl chloride) (PVC)/epoxidized natural rubber (ENR)/(Kenaf core powder) composites

The effects of dynamic vulcanization on properties of poly(vinyl chloride) (PVC)/epoxidized natural rubber (ENR)/(kenaf core powder) composite were studied. Tensile properties indicated that the strength, elongation at break, and Young's modulus of the composites exhibited an increase for samples with dynamic vulcanization. Morphological analysis using scanning electron microscopy showed the interaction between ENR and PVC. There was no bonding between kenaf core powder and the PVC/ENR matrix owing to the different polarity of both components. Filler agglomerates increased, which leads to an increase of filler‐filler interaction and poor dispersion. Furthermore, swelling index indicated that the composite with dynamic vulcanization shows lower absorption of tolune compared with composites without dynamic vulcanization. J. VINYL ADDIT. TECHNOL., 22:206–212, 2016. © 2014 Society of Plastics Engineers     

Synthesis and structural characterization of an alternating double aquo-bridged and single cyano-bridged polymeric barium–iron complex: {[Ba2(phen)4(H2O)6Fe(CN)6]·Cl·2(phen)·3H2O}n

A new alternating double aquo-bridged and single cyano-bridged polymeric complex {[Ba₂(phen)₄(H₂O)₆Fe(CN)₆]·Cl·2(phen)·3H₂O}_n (1) (phen = 1,10-phenanthroline) has been synthesized and structurally characterized. In the crystal structure the two centrosymmetric [Ba₂(phen)₄(H₂O)₆] units are bridged through two trans CN groups of [Fe(CN)₆]³⁻ ion, which results in the formation of a zig-zag polymeric chain. In each [Ba₂(phen)₄(H₂O)₆] unit, the two Ba centers are joined by double aquo bridges. Both the Ba atoms are 9-coordinated with distorted mono-capped square antiprismatic geometry. An elaborate hydrogen bonding system holds the parallel polymeric chains together.     

Determination of residual organic matter in extracted oil sands using a low temperature ashing method

The application of a low temperature ashing method for estimating total residual organic matter (toluene insolubles) in oil sands is described. A linear correlation exists between organic carbon content and loss on ignition at 400 ± 10 °C of solvent extracted oil sands. The ratio between total organic carbon and the weight loss on ignition (CT/LOl) owing to the removal of residual organic matter is much lower than that obtained for toluene soluble bitumen fractions, indicating very different chemical composition for the residual organic matter. The measured carbon content of the residual organic matter in oil sands suggests that this material could be a mixture of various fractions contained in resins, asphaltenes, asphaltic acids and humic acids.     

Increasing ethylene production as a high value hydrocarbon in Fischer-Tropsch (FT) reactor: A concept reactor for combining FT with oxidative coupling of methane

The paper proposes a concept configuration of reactors for coupling OCM and FTS, and presents systematic simulation results. FTS section is a combination of fixed bed and membrane fluidized bed reactor, and feed of the FT reactor is supplied by OCM. The reactor configuration is compared with the consecutive reactors of OCM and one fixed bed FT reactor. Effects of CH₄/O₂ ratio, percent of N₂ in the feed, contact time, and input temperature on the yield of ethylene and valuable hydrocarbons are studied. The results show that compared with one FTS reactor configuration, the dual FTS reactor configuration is more effective and thus gives much higher product yields. Furthermore, a main decrease is observed in the formation of CO₂ and CH₄.     

Radiation crosslinked polyvinyl alcohol/polyvinyl pyrrolidone/acrylic acid hydrogels: swelling,crosslinking and dye adsorption study

Iranian Polymer Journal - Hydrogels were produced from mixtures of polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), and acrylic acid (AAc) using γ-radiation at doses of 3, 7, and...